particle size in porous media??

Hi eveyone, Is me again. If i want to simulate a porous media, can i define my particle's size?? if yes how?? If no, what else can i do ?? becasue i may use different particles size for comparing the result..

for porous media model in Fluent, there is no option to let you choose particle sizes. you could only define momentum sink and in terms of porosity. you may have to define a multiphase model your problem where you could define material properties of differing diameters.